/**
 * 全局事件 
 * 启用侦听
 * 组件加载后添加侦听
 * eventBus.on('sayHi', sayHi)
 * 组件卸载之前移除侦听
 * eventBus.off('sayHi', sayHi)
 */
import  mitt from "mitt";
export default mitt()